• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.21-27
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• 2019

R-404A, which is used widely in small-scale ice makers, is scheduled to be phased out because of its high global warming potential. In this study, drop-in tests were conducted using R-448A and R-449A, which replace R-404A, to modify the outdoor air and supply water temperatures. The results showed that the daily ice production rate of R-404A was 5.3% higher than that of R-448A and 4.2% higher than that of R-449A. This was attributed to the larger vapor density of R-404A, which resulted in a larger mass flow rate in the system. Between R-448A and R-449A, R-448A yielded a larger amount of ice at low air and water temperatures, whereas R-449A yielded a larger amount of ice at high air and water temperatures. The daily power consumption of R-404A was approximately 10% larger than those of R-448A and R-449A. The resulting COPs of R-448A and R-449A was similar, only 3.0% larger than that of R-404A. The literature survey showed that the condensation or evaporation data of R-448A or R-449A are very limited, and research on this issue is recommended.

• Journal of the Korean Mathematical Society
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• v.59 no.3
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• pp.439-448
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• 2022

For a natural number n, let R(n) denote the number of representations of n as the sum of one square and five cubes of primes. In this paper, it is proved that the anticipated asymptotic formula for R(n) fails for at most $O(N^{{\frac{4}{9}+{\varepsilon}})$ positive integers not exceeding N.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.3
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• pp.446-448
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• 1989

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.448-449
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• 2005

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.5
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• pp.448-454
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• 2019

This paper presents a high-efficiency design technique for developing the serialized models of a single-channel pump based on the diameter, flow rate and head as the main performance parameters. The variation in pump performance by changing of the single-channel pump geometry was predicted based on computational fluid dynamics (CFD). Numerical analysis was conducted by solving three-dimensional steady Reynolds-averaged Navier-Stokes equations with the shear stress transport (SST) turbulence model. The tendencies of the hydraulic performance depending on the pump geometry scale were analyzed with the fixed rotational speed. These performances were expressed and evaluated as the functionalization for designing the serialized models of a single-channel pump in this work.

• The Journal of Korean Academic Society of Nursing Education
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• v.25 no.4
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• pp.448-458
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• 2019

Purpose: The aim of this study was to identify the effect of metacognition, communication skills, and confidence in the performance of core basic nursing skills on clinical competency in nursing students. Methods: A total of 158 students were recruited from two nursing colleges in B metropolitan city. Data were collected by means of self-reported questionnaires from December 3-31, 2018 and analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficients and multiple linear regression with SPSS 21.0. Results: Metacognition, communication skills, and confidence in the performance of core basic nursing skills were higher than normal and the relationship between the variables metacognition (r=.69, p=<.001), communication skills (r=.69, p=<.001), and confidence in the performance of core basic nursing skills (r=.59, p=<.001) were highly positively correlated with clinical performance. Factors influencing these three variables accounted for 64.4% of clinical competency. Conclusion: Further research on the development of the curriculum and intervention program, and the verification of the effect are needed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.447-448
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• 2008

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.448-453
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• 2011

Pre-aging heat treatment after solution heat treatment (SHT) of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn alloy sheets for auto-bodies was carried out to investigate the effect of pre-aging and its conditions on the bake-hardening response. Mechanical properties were evaluated by a tensile and Vickers hardness test. Microstructural observation was also performed using a transmission electron microscope (TEM). It was revealed that pre-aging treatments play a great role in the bake-hardening response. In addition, it was found that the sphere-shaped nanosized clusters that can directly transit to the needle-shaped ${\beta}$" phase during the paint-bake process, not being dissolved into the matrix, are formed at 343 K. The result, reveals that the dominant factor of the bake-hardening response is the pre-aging temperature rather than the pre-aging time.

• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.441-448
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• 2012

Let R be a prime ring with center Z and characteristic different from two, U a nonzero Lie ideal of R such that $u^2{\in}U$ for all $u{\in}U$ and $d$ be a nonzero (${\sigma}$, ${\tau}$)-derivation of R. We prove the following results: (i) If $[d(u),u]_{{\sigma},{\tau}}$ = 0 or $[d(u),u]_{{\sigma},{\tau}}{\in}C_{{\sigma},{\tau}}$ for all $u{\in}U$, then $U{\subseteq}Z$. (ii) If $a{\in}R$ and $[d(u),a]_{{\sigma},{\tau}}$ = 0 for all $u{\in}U$, then $U{\subseteq}Z$ or $a{\in}Z$. (iii) If $d([u,v])={\pm}[u,v]_{{\sigma},{\tau}}$ for all $u{\in}U$, then $U{\subseteq}Z$.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.355-365
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• 2016

This study was conducted to evaluate the relationships between emotional intelligence and college adjustment and nursing professionalism in nursing college students. The study participants were 172 nursing students of a university in Chungnam province. Data were collected by a self-administered questionnaire from December 1 to 20, 2015. Collected data were analyzed using the IBM SPSS 20.0 program with descriptive statistics, Pearson's correlation coefficient, t-test, one-way ANOVA and Scheffe test. The level of the emotional intelligence, college adjustment, and nursing professionalism were not high, and the emotional intelligence of nursing students had positive correlation with college adjustment(r=.448, p<.001)and nursing professionalism(r=.376, p<.001). These results suggest that nursing interventions to improve the emotional intelligence of nursing students should be developed and applied for improvement of college adjustment and nursing professionalism.